Apparatus for opening sheet metal seam locks



Aug. 1949- w. BIRKS 2,479,200

APPARATUS FOR OPENING SHEET METAL SEAM LOCKS FiledApril 28, 194' INVENTOR.

William Bz'rks BY v Patented Aug. 16, 1949 WilliamBirks, Meriaemeonn; Application April 28, 1947;. seriamduusn .7 f V This invention relates to apparatus for opening sheet metalseam locks; and'it relates more particularly to apparatus useful in preparing, for employment in construction work, a metal sheet having its margin suitably folded to provide the continuously recessed member of a seam lock such, for example, as the socalled Pittsburgh lockso widely employed by sheet metal workers,.

especially in fabricating pipe andduct workifor heating and ventilating system. H 7

Depending upon the particular type of machine employed to fold the margin of the flat sheet in vfcu rning the flange recess, i e. the recess which is to receivethe cooperating flange member of the seam lock, the ;meta1 folds may or may not have been forced so tightly together that before the product can be used, the walls of the recessforming fold must be wedged or pried apart in order to permit entry of the cooperating flange member thereinto. V ;In any event, even if the flange recess is left sufliciently, open by the lockforming machine, passing the sheet through forming or bending rolls to provide turns or other curved sections closes the lock recess, which must then be pried or wedged open,

This operation has b en quite generally performed heretofore by hand, by the so called plow-and-hammer method in which a screw driver or other wedging tool is first forced into thefiange recess and then driven the length of; the seam by means of a hammer to openit up; Although apparatus for opening such seam locks has been proposed heretofore, none of such prior proposals has proved sufficiently satisfactory and practical to attain widespreaduse in the sheet metal Working art. Among other disadvantages, such prior apparatus has been in the form of a machine complete in; itself and useless for any other purpose; thus representing an investment frequently idle for considerable periods of time, besides being relatively heavy, cumbersome and space consuming A specific object ofithe present inventiomthere-f" fore, is to overcome the disadvantages of such prior seam or look openers by providing a"set or group of cooperating seam-opening tools or tool members; constructed and arranged to, be detachably assembled with the base unit of what iscommonly known as a universal combination rotary machine, a type of machine on-which sheet metal working tools of various kinds can be detachably mounted in order to perform different operations on sheet metal. One form of such universal rotary machine is illustrated for example in the patent toPlatou 1,774,155. It is an advantage, accordingly, of the present invention that th utility of one machine need; not be limited to the re-opening or flaring of lock seams,

and a substantial economy in equipment is thus realized c V Another and more generalobject of the invenion.isiqi rqride ap a of relatively Simple cgnstruction for opening a recessed seam lock member preformed in the margin'of a metal'sheet, capable of operating effeetively upon such work Wmatherthej wq klbe. flat or curved; in which ppa tu ihlsea fl ei l Wei group. may or ma n be si s ab e r m i mums. and. iv n I a iFurther ob "ectsand advantages of the'iinve'n ips l Be o ia e isnif f hs lf isshown in the accompanying drawings and W111 I In order'that the nature'lof the invention may be fully understood anillustrative embodiment there'gf affording important practical advantages wiaiids abed; m an I t e drawings, Fi g i is aview in side elevation showing the noveltool set or group assembled in combination with supperting and driving means, the latter being provided, in this instance, by a metal Working machine base unitof the universal rotary tYIEYaDOve-ieferred'to1 up0n "which the tool set is detachably 'rno lntedf Fig. 2 is "a view in front elevation of Fig. 1; TFi'gj3 isa'view'ihplian of thelower part of the machine; certamparts being shown in section on line 3'-'"3 of' Fig .l 1, looking in the direction of the arrows;

'Figl4is a fragmentaryviewf partly in section on line 4-4'of Fig. 2, on an enlarged scale; and

v Figs, .5 and 6 are detail viewsin front elevation and perspective, respectively. 7

Referring now to the drawings; and at first more particumnygto FigsfI-3, that part of the apparatus which is des'igna'ted. generally as A, here shown in dotted lines for .the sake of differenti ation', is one characteristic 'form which the tool mo'unting base unit often takes in theaforesaid universalr'otary type of 'sheetmetal working machine. This'ibase unit, in and of itself, is old an'd'well knoWnQ In accordance with the pres-. ent invention, a novel seam-opening tool set shown in solidrlines and designated generally as His mounted, detachably in this instance, upon such a base unit to give a" combination or complete 'maehine assembly. capable of functioning in the desired manner. The invention comprises bothrthe combination and, also, as a separate entity or sub-combination, the novel tool set.

' 'Inthe operation of the apparatus, the work is fed through the machine by a pair of contrarotatin gltraction rolls, while a wedge-shaped flaring or'spreading tool is heldgengaged in the flange recess between the adjacent folds of sheet metal forming this member ef the seam 'lock. Passage of-the work through the machine thus causes the flaring tool to spread apart the adjacent folds of the closed-seam.

As shown in-Figs. landz the entire" apparatus is supported upon a bracket l having a socket l l at its upper end, in which base unit A is mounted for pivotal adjusting movement about a vertical axis and can be fixed in any adjusted position by means of set screw l2. Bracket It] may be provided at its base with suitable means, not shown, a

such means being in this instance a hand crank" 16, although a motor may of course be employed. As is usual in base units of this type, one of the arbors is angularly movable with respect to the other in order to adjust the distance between their tool-supporting ends as may be necessary in order to properly correlate the cooperating working surfaces of the rotary tools to be attached thereto, or to facilitate inserting work between the rolls by a direct thrust parallel to their axes. In this instance, arbor i4 is journaled at the rear of the unit in abearing H which is trunnioned on frame l'3, as indicated at I'Ia, for pivotal movement about ahorizontal axis perpendicular to the arbor axis. At its forward or tool-bearing end, the arbor is carried in a bearing block l8 which is laterally confined between and vertically movable in guides 18a provided at the forward end of the frame. Suite able spring means (not shown) urges bearing 18 toward its uppermost position in frame t3, and the block can be moved to andheld in any intermediate position by turning the adjusting screw rod F9 which bears against the upper surface of the block, through actuation of crank 20;

Keyed to arbors l4 and I5, respectively, within frame I3 are intermeshing gears Ma. and [a. which cause the arbors, when driven, to rotate in opposite directions. I

The set of tool members which is. to be combined with unit A is indicated at B aforesaid. It comprises traction rolls 2| and 22 which, at their forward ends, are of the same diameter, an adjustable bed or base plate 23, and a seamopening or flaring tool 24 mounted uponv the plate. Rolls 2| and 22 arerigi'dlyfbut removabl'y secured to the forward ends 'of arbors 1'4 and I5, respectively. As here shown, said rolls are hollow and are interiorly formed to permit the hub portion H of each to be slipped on over the reduced and threaded end portions I46 and lib of the respective arbors in such manner as to effect driving engagement between a projecting lug or key L on the arbor and a cooperating recess R in the rear face of the hub; this driving engagement being maintained by turning threaded 'co1-' lar or nut N on the forward end of each arbor up solid against shoulder S. In order to increase the tractive effort of the rolls on the work W (Fig. 4), the rolls most desirably have their immediately adjacent peripheral working surfaces knurled. To the rear of the relatively narrow knurled working surface of upper roll the roll diameter is reduced to provide inclined'steps or shoulders 2m, 2111, Me, thepurpose-ofwhichwill appear hereinafter.

chine frame in perpendicular relation to the roll Bed plate '23, located be tween the rear faces of said rolls and the 'ma-- 4 axes, not only serves to support flaring tool 24, but also to provide a guide or gauge against which the rear longitudinal edge of the work (i. e; the edge ofthe hammer-over margin of the Pittsburgh lock member with which the a work is shown provided in Fig. 4) is automatically held in firm abutment as the work passes through the machine. The plate is adjustably mounted upon frame I3, for limited movement parallel to the arbors, by means of a. pairv of studs 25, 26, which are secured to and project rearwardly from the rear face of the plate into apertures in bosses 21 and 28, respectively, provided at opposite sides of the frame. In this instance, stud 26 extends completely through boss 28 and wen into an aperture in a second boss 29 at the rear of the machine, its threaded rearmost 'portionifia being engaged in an internally threaded sleeve 32 rotatable in said aperture but held against longitudinal movement. By means of operating knob 31, the sleeve may be turned to move the stud 26, and hence the bed plate, forwardly or rearwardlly as may be necessary to properly adjust the position of the gauging face of the bed plate relative to the traction rolls. Stud 25 may, if desired, be similar to stud 26, and similarly held in adjusted position; but in practice it has been found that su'fiiciently rigid mounting of the bed plate is attained by having stud 25 only long enough to project into the aperture in front boss 21, without being anchored therein, since when thus dis- 1 posed it acts effectively'both to assist in properly supporting the base plate and also to prevent turning movement thereof transversely with respect to arbors I4, IS.

The adjustability of plate 23 toward or awayfrom the traction rolls permits accommodating work having lock seam members of different 235 in its lower portion, these apertures being vertically alined centrally of the plate.

Flaring tool 24, which is carried by plate 23 as previously mentioned, is so mounted on said plate as to be rotatable about a fixed vertical axis, with its flaring edge projecting horizontally forward and just above the knurled periphery of roll 22, clearing it by a distance only very slightly greater than the thickness of the sheet metal to be worked. In this instance, the flaring tool consists of a circular disc 240. which is relatively thick at its center but tapers to a thin edge at its periphery. As here shown, one face (the under face) of the disc is plane, while the other slopes inwardly from the thin periphery up-' wardly to a central locality of maximum thickness at which there is provided an axial mounting stud or pivot pin 24b perpendicular to the plane under face or side of the disc. Notch 23a of the bed plate is deepened centrally to provide a relatively shallow rectangular recess or subnotch 23c extending between shoulders 23d and projecting central portion 34b apertured at 34c and a plane undersurface, is supported at its ends on shoulders 23:1 to which it is secured by machine screws 35 after the flaring tool has been placed imposition with approximately one! half of the plane face of flaring disc 24a bearing against the bottom of recess 23c and with mounting stud 24b projecting vertically upward into yoke aperture 340. Said stud is received in aperture 34c witha bearing fit permitting free rotation but sufliciently close to prevent appreciable lateral movement. It will be seen that the axis of rotation is substantially in the plane of the parallel arbor axes. Clearance between the retaining yoke and the flaring disc where the latter is thickest (at the bas of the mounting stud), while suflicient to permit free rotation of the tool, is insuflicient to permit appreciable vertical movement thereof. v V

In operating the machine, the sheet metal work to be prepared for use can be passed through it in either direction, (i. c-. right or left in Fig. 2) depending upon the angular direction in which the traction or feed rolls 2i, 2!, are driven. In practice, before starting a piece of work through the machine, it is usually advisable, although not indispensable, to open the closed flange recess slightly at its leading end, in order to make certain that the edge of the rotary flaring disc may at the outset be properly engaged between the walls of the recess. This initial opening may be accomplished in any suitable manner as by means of a prying'or wedging tool, for example. The work, with its edge held against plate 23 as a guide, as shown in Fig. 4, can then be inserted into the pinch between the traction rolls, the flaring disc entering the opened leading end of the recess and, as the work is fed against it by the action of the traction rolls, progressively opening the recess smoothly and uniformly throughout its entire length. Instead of making use of a separate tool to effect the initial opening up of the recess at its leading end, it is often more convenient to accomplish this in another way. Thus, the gap between the traction rolls is first enlarged sufficiently, by swinging arbor l4 up through manipulation of adjusting crank 20, to permit the leading margin of the work to be thrust transversely between the rolls (1. e. parallel to their axes) despite the three thicknesses of metal at the seam, and'the single-thickness portion to the rear of the'seam to be forced into the small clearance between the lower roll and the now stationary horizontal flaring disc far enough to engage the hammer-over edge firmly against plate- 23. Simultaneously the leading end of the folded flange recess is forced against the thin edge of the flaring disc, which enters and opens the recess to a depth predetermined by the setting of the bed or gauge plate. The adjusting crank 28 is then turned to force arbor [4 down until the knurled portion of roll 2! engages the sheet metal Work firmly enough to exert thereon, in conjunction with roll 22, the desired tractive or feeding action when the rolls are driven by operating crank :6. At the same time, the lowering of roll 2! into this position sets the cylindrical forward portion of the roll down against the work with its rear edge or shoulder am just in front or and engaging the forward edge of the slight ridge or thickening produced by the metal folds of the flange recess, thereby preventing movement of the work forward-away from the gauge plate; which would otherwise result because of the horizontal forward reaction thrust of the flaring tool'disc on the work in entering and opening the recess as thework is'fedag-ainstthe disc in the ensuing operation of the machine. Further-i more, the construction and arrangement of the cooperating parts is such. that deformation of the hammer-over or standing edge portion through being bent downwardly in the seamopening operationis effectively prevented.- In the first place, the hereinabove described mounting of the flat-bottom flaring tool on the .bed plate precludes any appreciable tilting of its disc out of horizontal through the downward thrust exerted upon its margin by the work in resisting its seam-opening action. But, in addition, the entire width or depth of Work: margin being operated upon at any given instant is solidly backed up from below by theworking surface of uniform-diameter lower roll 22, as is best shown in Fig. 4, thus ensuring smooth and accurate ironing of the work on both sides of the seam folds as they are being opened, and hence maintaining the parts of the seam lock member in proper form and alinement. l

, From the foregoing,; it will be apparent that, by reason of its adjustable mounting on unit A, the bed or gauge plate can be set to cause the flaring tool disc to enter the flange recess to any desired depth, within practical limits, and thereby to open the recess to a corresponding predetere mined extent. Moreover this action of the tool, will be accurately uniform throughout the entire length of the work operated upon, because at all times during its travel through the machine, the work is positively confined and held against transverse or lateral displacement by the engagement of the gauge plate with the rear edge of the work, on the one hand, and the engagement of the-aforesaid shoulder'of roll 2| withtheforward edge of the aforesaid thickening at the seam base, onthe other. The inclined step 2|b just to the rear of said shoulder 2| a on the upper traction roll permits outward movement of a wall of the flange recess as the latter is entered by the-flaring tool. The further inclined step He provides for clearance between the roll and the forwardly projecting portion 34b of retaining bar 34.

The flaring tool rotates about its vertical axis due to its frictional contact with the closed recess walls between which it progressively enters and which-it wedges or plows apart as the Work is fed-through the machine. Much less power-is required than as though the flaring tool were not rotatably mounted, and embodiments of the invention in which the flaring tool is rotatably mounted aretherefore far superior and greatly to be preferred.

While, as already pointed out, the novel seam,- opening apparatus will operate effectively on fiat work, its ability to handle bends and curved shapes generally, always with such notably satisfactory results, is of especially outstanding practical importance for sheet metal workers. Achievement of this reat, advantage is. made possible by the manner in which the parts of the tool assembly cooperate in the arrangement hereinabove described, whereby a curved section being operated upon is compelled, by the laterally confining effect thereon resulting from engagement therewith of the shouldered upper roll acting in conjunction with the vertical gauging face plate 23 against which the work abuts at the rear, to travel through the machine in a path parallel to andin front of said vertical gauging face. As will .be apparent from Figs. 2 and 3 especially, plate 23 extends a considerable distance from the roll pinch both vertically and horizontally, there by enhancing the above mentioned confining efaerator:

feet. Accordingly, regardless of their length or specific form, curved sections can be readily handled through the machine without inter- 'ferenoe with or obstruction of the travel of the work by contact with 'a part of the apparatus itself, or with the work bench or standard .on which it is mounted, a disadvantage which has characterized some seam-opening apparatus heretofore proposed. In the apparatus of the ptesent invention, with the novel tool set or combination assembled with the base unit and overhanging .itheedge of the bench (e. g.), the curved section can extend and travel either above 01 below, or both above and below, the benchlevel and iii-either direction, without encountering any obstruction icy-the bench or any part of the ap paratus itself.

, What is "claimed is:

.1. :Ihe combination, in a sheet metal working machine toolias'sembly which is adapted and arranged to separate adjacent folds of sheet metal work having a pre-iormed seam io'ld along one margin, of .a pair of 'contra-rotating, mutually cooperating traction rolls adapted to receivesuch workibetween them andto advance itthrough'the machine, a bed plate adjacent said rolls against which the margin of such work abuts and is gulded as it isadvanced, and a'flaring tool carried i-bylsaid sbed plate and projecting into the path :"of movemcntof such'work, said flaring tool being:adapt'edlandarrangedto enter progressivelyibetween adjacentwalls of said marginal seam fold and to cause the flaringapart thereof as the workiis advanced through themachine.

'h tool set ortgroup constructed and adapted V iorrattachment to the base unitof a sheet metal workirr'glmachine of the universal rotary type to adaptsuch a machine for re-opening a-lock seam having 'a iiange recess folded into the margin ofssheetmetal work, sai'ol'set or group comprisingsa pairzzofirolls, a gauge plate-and a rotary flaring 1001, all .as further defined in claim 1, aiidiibelng-adapted for assembly with the base unit oiiaa unive'rsal rotary type machine'as and iorflzl iepu'rposes set forth in said claim.

+3. '-I'n av-sheet metal working =machine, a detachabletool assembly comprising, in combinatioma pair of mutually 'co-acting traction rolls, between which sheet metal work having a'seam toldr'along one margin is adapted and arranged to loezpassedrby'the-contra-rotation of said rolls, aiieh plate adjacent said rolls against which theedgeofrthe.marginal seam fold abuts in passing through the machine, and a flaring tool'c'arriedibysaid bed plate, said tool projecting into the path of said marginal seam fold as it is ad tanned through the machine and adapted and arranged :to enter'progressively between adjacentliol'd's of said seam fold and to effect a separation rthereof.

4.: In a sheet metal working machine for manipulating'work havmg amarginal seam folded totpr'ovide aflange recess, said machine having a pair of substantially .paraliel arbors suitably journaled for rotation therein and driving means for-rotating said arbors'ih opposite directions, the combinationwhich c'o'in prisesa pair of mutuaiIy -coop'erating traction rolls for engaging and progressing sheetmetal work between them, said rolls being :securedto the outer ends of said arbors and carried thereby, a guide :plate against which :the :margin' of such work abuts and is guided in passing through the .machine,.said plate being mounted: 'on said machine adjacent the innersurfaces ofsaid rolls and substantially perpehiiicular to their iaxes of rotation, and :a flar ing tool mounted on said guide plate to project outwardly therefrom, adapted and arranged to enter zthe flange s-recess between adjacent seam folds of such marginally 'seam folded work as itzprogitessesthrough the machine .and to efi'ect a separation :of :such zadjacent ;.seam .folds.

:5. A atool .set :or group constructed :and adapted for attachment to :the base vunit :of :asheet metal working machine eof the universal rotary type to adaptzrsuch faxm'achine for reeopening a Jock seam having aifi'ange lrecess folded into the margin of sheet metal work, said set'or group :comprising "a pair :of rolls, ca gauge :plate and a rotary rfiaring tool, all 2545 further defined in claim :4, and

being adapted :for assembly with the r-hase unit of a universal rotary type .;machine as and .for the purposes set forth in said claim.

:6. inasheet metal working machine for opening :lock seams having a flange recess formed in the margin .of. sheet metal work, said machine having a pair of substantially parallel arbors suitably journaled for rotation therein and .driv ing means iior rotating *said arbors in opposite directions, @the combination which comprises ,a vertically disposed ,work "guiding plate against which zthe edge of :the lock seam abuts, vertically opposed 'tractionqrolls mounted on .said arborsadjacentsaidaplate, saidrolls being adapted to engage such work between their tractive surfaces and to advance it in either direction through athemachin'e, 'and a flange recess opening tool carried by saidtwork-guiding plate and disposed in substantial alignment with the adjacentsurface's fofsaid traction rolls to cause it to enter between and separatethe walls of such flange recess as such work isadvancedthrough the machine.

7. A tool set or group constructed and adapted for attachment to the base unit of a sheet metal working :inachine of :theuniversal rotary type to adaptsuch acmachine forfre-opening a lock seam having aflangerrecess folded into the margin of shee'tlmetal work, saidsetor group comprising a pair 'of-roils, a gauge'plate and a rotary flaring tool, all as further defined in claim 6, and being-adaptedforassembly with the base unit of a univer'sal rotary-type imachine as and for the p urposesiset;forthrin :said claim.

8. In a-Vuniversal'rot-ary type sheet-metal workingmiachinethe combination, with a base unit which includes-a frame supporting a pair of substantially; parallel power driven arbors journaled forrotation-in opposite directions about super pos-ed horizontal.-axes,-ofa: set or group of tools assembled with said base unit and adapting the machine iorropening theflange recess of a lock seam'forme'd in:the marginalportion of sheet metal work, said-set or group comprising avvertically=disposed platemember against which the seamed edgegofwsaid sheet metal 1 work abuts and is guided in passing through themach-ine, means for securingsaid .platevto'the 'base'frame, a relativei'y thin-edged :d-isc secured. to and supported byisaid plateimember for rotation about a .vertical axis-the adiameter'of said disc being sub. stantially'greater than the thicknessof said plate member to cause a'portion or its periphery to project horizontally-beyond the face of said plate, andf'a pair of :vertically opposed traction rolls afiixedx'to the: ends of said arbors adjacent said plate:member,--said rollshaving peripheral surfaces whichicomierate mutually-at a point insubstantiaraiignrhent withthe projecting periphery oisaiddisc and are adapted to engage the work 9 between them at such point to advance it past said disc to cause the latter to progressively enter between and separate opposite walls of said flange recess as the work is advanced through the machine.

9. The machine set forth in claim 8, in which said plate member is notched downwardly centrally of its face to provide shoulders on opposite sides of the notch and said disc is mounted between said shoulders and journaled in a yoke extending between and secured to said shoulders.

10. The machine set forth in claim 8, in which the thickness of said disc tapers outwardly from the edge thereof to provide a wedge-shaped peripheral margin on said disc.

11. The machine set forth in claim said plate member is provided with mounting studs extending perpendicularly from the rear face of said plate member, said studs being adjustably secured in apertures provided in the frame of said machine. a I

12. A tool set or group constructed and adapted for attachment to the base unit of a sheet metal working machine of the universal rotary type to adapt such a machine for re-opening a 8, in which 15. A set of cooperating seam-opening tool members constructed and adapted for assembly with a universal type rotary sheet metal working machine base unit which includes a frame and a pair of substantially parallel contra-rotatable arbors supported thereby, said set comprising the following members which, when in such assembly, are in the hereinafter specified relationship to said unit and to each other: a pair of traction rolls mounted on said arbors and having mutually cooperating peripheral surfaces for engaging and advancing between them, upon contra-rotation of the rolls, sheet metal work having a seam fold along one margin, the advance being in a direction parallel to said fold; a guide plate supported by said frame adjacent said rolls against which the edge of the marginal seam fold abuts as the work is advanced through the machine; and a flaring tool carried by said guide plate, said tool projecting into the path of said marginal seam fold as it is advanced through the 7 machine, and being adapted and arranged to enter progressively between the adjacent folds I of the seam and to effect a separation thereof.

lock seam having a flange recess folded into the V margin of sheet metal work, said set or group comprising a pair of rolls, a gauge plate and a rotary flaring tool, all as further defined in claim 8, and being adapted for assembly with the base unit of a universal rotary type machine as and for the purposes set forth in said claim.

13. Apparatus for opening sheet metal seam locks which comprises a pair of driven rolls mounted with their axes parallel and vertically superposed, adapted and arranged to engage between their peripheries sheet metal work having a seam fold marginally pre-formed therein parallel to the adjacent end of the work, and to feed the work in a path parallel to such fold, the lower roll being of uniform diameter over its entire working face, while the upper roll is of uniform diameter over only the forward portion of its periphery and is shouldered to reduce itsdiameter over the remaining portion, a gauge plate mounted to present, adjacent the rear ends of said rolls but spaced therefrom, a plane gauging face perpendicular to the roll axes, the mounting of said plate being adjustable to permit moving it toward or away from the rolls, a flaring tool mounted on said plate for rotation about a vertical axis in the plane of the roll axes and having a flat-bottom circular flaring disc which projects forwardly from said gauging face to overlie closely a rear portion of the lower roll periphery and adjusting means operable to so position said plate that the horizontal distance between its vertical gauging face and the forwardmost shoulder on the upperjroll is substantially equal to the distance between the rear edge of the work and the base of the seam fold pre-formed therein.

14. A tool set or group constructed and adapted for attachment to the base unit of a sheet metal working machine of the universal rotary type to adapt such a machine for re-opening a lock seam having a flange recess folded into the margin of sheet metal work, said set or'group comprising a pair of rolls, a gauge plate and a rotary flaring tool, all as further defined in claim 13, and being adapted for assembly with the base unit of a universal rotary type machine as and for the purposes set forth in said claim.

16. A set of cooperating seam-opening tool members as defined in claim 15, constructed and adapted for assembly with a base unit of the stated type which has its arbors horizontally disposed; the said members, when in such assembly, being in the specified relationship, with said traction rolls in vertical alignment, said guide plate having a flat face positioned adjacent said rolls at the rear thereof and perpendicular to their axes, and said flaring tool projecting horizontally from said plate toward and between said rolls.

17. A set of cooperating seam-opening tool members as defined in claim IS, in which said flaring tool is a circular disc having a wedgeshaped edge; which disc, in such assembly, is supported by said guide plate for free rotation about a substantially fixed vertical axis in the plane of the parallel horizontally disposed axes of said arbors.

18. A set of cooperating seam-opening tool members as defined in claim IT, in which said circular disc is plane on one face and is provided on the other with an axial mounting stud, while said guide plate is formed with a recess to receive said disc with its plane face seating therein; said set further including a retaining member apertured to receive said mounting stud and adapted to be secured to said plate in order, when the parts are assembled, to maintain said axis of rotation substantially fixed.

19. A set of cooperating seam-opening tool members as defined in claim 15, in which said flaring tool is a circular disc of thickness decreasing towards its periphery; which disc, in such assembly, is supported by said guide plate for free rotation about a fixed axis in the plane of and perpendicular to the parallel axes of said arbors.

WILLIAM BIRKS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,146,659 Stewert Feb. '7, 1939 2,334,407 Grebe Nov. 16, 1943 

